Radiation Reflection Device

ABSTRACT

A radiation reflection device used to focus radiation from a moving source onto a stationary receiver is disclosed. The primary application of such an invention relates to reflecting the radiation from the sun onto a stationary target. The device orients a reflective surface to a position necessary for imaging using a parallelogram type half-angle system. The device may be used singly or in a ganged array.

BACKGROUND OF THE INVENTION

The present invention relates to a radiation reflection device used tofocus radiation from a moving source onto a stationary receiver.

The primary application of such an invention relates to reflecting theradiation from the sun onto a stationary target. In such an application,wherein the device is used to orient a reflective surface to reflectlight onto a target, the device may be termed a “heliostat”. In anothersunlight reflecting application, wherein the device is implemented in anarray used to orient a plurality of reflective surfaces to reflect lightonto a target, the device may be termed a “ganged heliostat”. Lightconcentration achieved by heliostats or ganged heliostats has severaluses which include thermal energy conversion, photovoltaic energyconversion, and daylighting.

In other applications, the device may be used to reflect any other typeof electromagnetic radiation such as radio signals, sound waves,moonlight, etc.

PRIOR ART

A prior art exists in heliostat devices. Various heliostats of the priorart require complex computer control of encoder type servo or steppermotors such as the device disclosed in U.S. Pat. No. 4,440,150(Kaehler). Various heliostats of the prior art require a half-anglegearing system such as the devices disclosed in U.S. Pat. No. 5,027,047(Logan et al.) and U.S. Pat. No. 4,586,488 (Noto). Various heliostats ofthe prior art require an external sensor feedback system and complicateddrive arrangement such as the device disclosed in U.S. Pat. No.6,899,096 (Nakamura). The present invention, when employed in aheliostat, does not require a complicated external computer control,encoder type motors, or a half-angle gear system.

A prior art exists in ganged heliostats such as devices disclosed inU.S. Pat. No. 4,110,010 (Hilton), U.S. Pat. No. 4,056,313 (Arbogast) andU.S. Pat. No. 3,466,119 (Francia). These devices include a high numberof parts and a high complexity of parts. Also, various ganged heliostatsof the prior art (e.g. U.S. Pat. No. 4,110,010) require daily adjustmentto compensate for the declination of the sun. Such a requirementincreases operating cost of the device and the likelihood of focusingerrors. The present invention, when employed in a ganged heliostat, doesnot require continual adjustment to compensate for solar declination andis simpler in construction than ganged heliostats of the prior art.

BRIEF SUMMARY OF THE INVENTION

The present invention relates to a radiation reflection device which canbe used to orient a mirror to reflect radiation from a moving radiationsource to a stationary receiver. The device can be used either singly,or implemented in a ganged array.

The device includes a reflective surface, or mirror and a mirror framewhich is attached to the mirror. The device orients the mirror to aposition bisecting the incidence vector (i.e.—a vector through themirror centre and the source of radiation) and the reflection vector(i.e.—a vector through the mirror centre and the stationary receiver),thus achieving the reflection of light from source to target (imaging).

The device includes a linkage that is aligned perpendicular to theincidence vector. This linkage is referred to as the incidence linkage.The device includes a linkage that is aligned perpendicular to thereflection vector. This linkage is referred to as the reflectionlinkage.

The incidence linkages and reflection linkages are interconnected in aparallelogram pattern. Vertices of the parallelogram pattern define aparallelogram bisecting line that bisects the angle between theincidence and reflection linkages. The device includes traversing boltsthat pass through the vertices of the parallelogram bisecting line. Thetraversing bolts also pass through slots of the mirror frame andindirectly locate the mirror to a position necessary for imaging.

The advantages of the present invention will be more apparent from thefollowing detailed description in reference to the accompanyingdrawings.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a conceptual elevation view of embodiment ‘1’ of the inventionin relation to a source of radiation and a target wherein the device isimplemented in a heliostat

FIG. 2 is a top view of the heliostat of FIG. 1 in the neutral position

FIG. 3 is a side view of the heliostat of FIG. 2 taken along the line3-3

FIG. 4 is a front view of the heliostat of FIG. 3 taken along the line4-4

FIG. 5 is a side view of the heliostat of FIG. 2 in an alternateposition

FIG. 6 is a side view of embodiment ‘2’ of the invention wherein thedevice is implemented in a heliostat

FIG. 7 is a conceptual elevation view of embodiment ‘3’ of the inventionin relation to a source of radiation and a target wherein the inventionis implemented in an element of a ganged heliostat

FIG. 8 is a top view of the ganged heliostat element of FIG. 7 in theneutral position

FIG. 9 is a side view of the ganged heliostat element of FIG. 8 in analternate position

FIG. 10 is a top view of embodiment ‘4’ of the invention in the neutralposition wherein the invention is implemented in a heliostat

FIG. 11 is a side view the heliostat of FIG. 10 in an alternate position

FIG. 12 is a top view of embodiment ‘5’ of the invention in the neutralposition wherein the invention is implemented in a heliostat

FIG. 13 is a side view of the heliostat of FIG. 12 taken along the line13-13

FIG. 14 is a side view of the heliostat of FIG. 13 taken along the line14-14

FIG. 15 is a top view of embodiment ‘6’ of the invention in the neutralposition wherein the invention is implemented in a heliostat

FIG. 16 is a side view of the heliostat of FIG. 15 taken along the line16-16

FIG. 17 is a side view of the heliostat of FIG. 16 taken along the line17-17

FIG. 18 is a side view of the heliostat of FIG. 15 in an alternateposition

FIG. 19 is a side view of a ganged heliostat element of a deviceemploying the wire type reflection aiming means and a half-angle gearingsystem

DETAILED DESCRIPTION OF USEFUL EMBODIMENTS OF THE INVENTION

Six embodiments of the invention will be described: embodiment ‘1’,embodiment ‘2’, embodiment ‘3’, embodiment ‘4’, embodiment ‘5’, andembodiment ‘6’. The embodiments ‘1’, ‘2’, ‘4’, ‘5’, and ‘6’ areheliostats and embodiment ‘3’ is a ganged heliostat. Each embodimentwill be described with respect to a solar reflecting (concentrating)application.

The heliostat of embodiment ‘1’ will now be described with reference toFIGS. 1 through 5. FIG. 1 shows the heliostat reflecting sunlight fromsource ‘S’ to a receiver ‘R’. To achieve imaging a reflective surface,mirror 1204, mounted on mirror frame 1203 is positioned such that thenormal of the mirror (i.e.—a vector perpendicular to the mirror surfacecoincident with the mirror centre) bisects the angle between theincidence vector (i.e.—a vector from the source to the mirror centre)and the reflection vector (i.e.—a vector from the mirror centre to thereceiver). The mirror frame 1203 is positioned indirectly by pan motor1101 and tilt motor 1102. The mirror, mirror frame, incidence linkages,reflection linkages, motors, and various other parts of the heliostatare mounted on a carriage which is mounted on, and rotates about, a mainshaft 1001. During the initial set-up of the heliostat, the main shaft1001 is fixed to stationary post 1003 using bracket 1002 in such amanner that the central axis of main shaft 1001 is coincident with(i.e.—“pointing at”) the receiver.

FIG. 2 shows the heliostat in the “neutral position”. The heliostat isin the neutral position when the incidence vector and the reflectionvector are coincident and opposite. FIG. 2 shows incidence linkages1301, 1303, 1400, 1402, and 1404, and reflection linkages 1300, 1302,1304, 1401, and 1403. FIGS. 3 and 4 provide further detail of theheliostat in the neutral position. The linkages and motors are mountedon a carriage consisting of carriage base 1601, carriage posts 1603, panmotor plate 1604, and tilt motor plate 1605. The carriage base 1601 ismounted on, and rotates about, main shaft 1001.

Tilt motor 1102, which is fixed to the carriage at tilt motor plate1605, is fixed to linkage 1400 at its centre of rotation. Pan motor 1101is fixed to coupling 1602, which is fixed to main shaft 1001. Pan motor1101 and tilt motor 1102 are controlled to continually adjust incidencelinkage 1400 such that it remains perpendicular to the incidence vector.Reflection linkage 1300 is fixed to the carriage posts 1603 such that itis perpendicular to the main shaft 1001. Since main shaft 1001 iscollinear with the receiver, linkage 1300 is always perpendicular to thereflection vector.

Each of the linkages includes three holes; one at the centre and one ateither end. The distance between the centre hole and either end-hole isthe same for each linkage. Linkage 1401 is connected to linkage 1400 atone end and linkage 1402 at the other end. The joints between linkages1400 and 1401 and between linkages 1401 and 1402 are rotatable.Similarly, linkage 1301 is connected to linkage 1300 at one end andlinkage 1302 at the other end. The joints between linkages 1300 and 1301and between linkages 1301 and 1302 are rotatable. Traversing bolt 1501passes through the centre hole of linkages 1301 and 1401 and through themirror frame guides 1201 and mirror frame guides 1202. Traversing bolt1502 passes through the centre hole of linkages 1302 and 1402 andthrough mirror frame guides 1201 and mirror frame guides 1202. A bolt atthe centre of linkage 1300 passes through a sleeve fixed to the centreof guides 1201. A bolt at the centre of linkage 1400 passes through asleeve fixed to the centre of guides 1202.

The function of linkages 1301, 1302, 1401, 1402 is similar to thefunction of linkages 1303, 1304, 1403, 1404. The function of traversingbolts 1501, 1502 is similar to the function of traversing bolts 1503,1504.

FIG. 5 shows the heliostat of embodiment ‘1’ in a position other thanthe neutral position. A line through the traversing bolts 1501, 1502,1503, 1504 bisects the angle between linkages 1300 and 1400. Note thatthe incidence linkages and reflection linkages are interconnected in aparallelogram pattern. Therefore, when linkages 1300 and 1400 areperpendicular to the reflection and incidence vectors respectively, aline through the traversing bolts will define the mirror positionnecessary for imaging. The traversing bolts define the position of themirror frame guides. The mirror frame guides 1201 and mirror frameguides 1202 are fixed to the mirror frame 1203. The mirror frame 1203 isfixed to the mirror 1204. Therefore the traversing bolts indirectlyachieve the mirror position necessary for imaging.

It should be noted that the centre of mass of the rotating parts of thedevice coincides with the central axis of the shaft of pan motor 1101and the central axis of the shaft of tilt motor 1102. Therefore, thetorque requirement of the motors is minimized.

The heliostat of embodiment ‘2’ is shown in FIG. 6. The heliostat ofembodiment ‘2’ functions in a similar manner to that of embodiment ‘1’with several differences. Embodiment ‘2’ employs 4 interconnection partsand 2 traversing bolts whereas embodiment ‘1’ employs 8 interconnectionparts and 4 traversing bolts. Embodiment ‘2’ is unstable in the neutralposition. Embodiment ‘2’ is stable and capable of imaging in positionsother than the neutral position. Embodiment ‘2’ employs fewer parts thanembodiment ‘1’.

Embodiment ‘2’ includes a sensor feedback system used to control panmotor 2101 (analogous to pan motor 1101 of embodiment ‘1’) and tiltmotor 2102 (analogous to pan motor 1102 of embodiment ‘1’). Pan sensors2804 and 2805 are fixed to the carriage posts 2603. Tilt sensors 2802and 2803 are fixed to the incidence linkage 2400. The sensors are of thephotovoltaic type or photoresistor type. The sensors send signals to anelectronic control system used to control pan motor 2101 and tilt motor2102.

Pan motor 2101 rotates the heliostat carriage until the sunlightincident on pan sensors 2804 and 2805 is equal (i.e.—the sensor pair isbalanced). Tilt motor 2102 rotates linkage 2400 until the sunlightincident on tilt sensors 2802 and 2803 is equal (i.e. the sensor pair isbalanced). When each sensor pair is balanced, linkage 2400 has achieveda position wherein it is perpendicular to the incidence vector. Oncethis is achieved, the mechanism of the heliostat causes the reflectivesurface to be oriented for imaging as described above. A sensor feedbacksystem of this type allows non-encoder type motors (e.g.—DC gear motors)to be employed as pan motor 2101 and tilt motor 2102.

It should be noted that initial setup of the heliostat is easilyachieved. During setup, the main shaft 2001 is aimed at the receiver. Nofurther calibration is necessary. The device does not require any typeof periodic adjustment.

The ganged heliostat of embodiment ‘3’ will now be described withreference to FIGS. 7 through 9. FIG. 7 shows an element of the gangedheliostat reflecting sunlight from source ‘S’ to a receiver ‘R’. Anotable difference between the heliostat embodiments ‘1’ and ‘2’ and theganged heliostat embodiment ‘3’ relates to the main shaft 3001(analogous to main shaft 1001 of embodiment ‘1’). In the gangedheliostat embodiment, the main shaft 3001 is continually adjusted insuch a manner that the central axis of main shaft 3001 is coincidentwith (i.e.—“pointing at”) the source of radiation. The adjustment ofmain shaft 3001 is achieved by an aiming means, various types of whichare known in the prior art. Wire 3701 is attached at one end to thereceiver and at its other end to a reflection linkage of the device.Wire 3701 defines the reflection vector and as such provides areflection aiming means, main shaft 3001 defines the incidence vector,and the mechanism comprising the linkages, traversing bolts, guides, andframe of the device define the mirror position necessary for imaging.

FIG. 8 shows an element of the ganged heliostat of embodiment ‘3’ in theneutral position. FIG. 9 shows the element of FIG. 8 in a position otherthan the neutral position. The ganged heliostat element has a verysimilar form and function to the heliostat of embodiment ‘1’. Reflectionlinkage 3400 (analogous to incidence linkage 1400 of embodiment ‘1’) isconnected to the split ends of wire 3701 at holes 3702 and 3703. Thesplit ends of wire 3701 are equal in length. When wire 3701 is put undertension, linkage 3400 is aligned to a position perpendicular to thereflection vector.

Incidence linkage 3300 (analogous to reflection linkage 1300 ofembodiment ‘1’) is mounted on, and rotates about, main shaft 3001 whichis adjusted by the incidence aiming means. Therefore, the incidenceaiming means indirectly aligns linkage 3300 to a position perpendicularto the incidence vector. When linkages 3300 and 3400 are aligned topositions perpendicular to the incidence and reflection vectorsrespectively, the mechanism comprising the linkages, guides, and mirrorframe achieves a mirror position necessary for imaging.

It should be noted that the centre of mass of the rotating parts of thedevice lies midway between the split ends of wire 3701. Therefore, thetension requirement of 3701 is minimized.

Optionally, an additional wire 3706 (not shown in the Figures) may beemployed in the ganged heliostat element. Wire 3706 would include aplain end and a split end (similar to wire 3701). If employed, the wire3706 would be connected at its plain end to the receiver, and at itssplit end to holes 3704 and 3705. When put in tension, wire 3706,together with tensioned wire 3701, adjust and position the reflectionlinkage.

The novel reflection aiming means achieved by wire 3706 may also becombined with the half-angle gearing method used in heliostats of theprior art as shown in the device of FIG. 19. This device of FIG. 19 willnow be described.

A reflection linkage that is positioned using the wire type reflectionaiming means is connected to a gear G1. Gear G1 turns gear G2 whichturns gear G4 which turns gear G6 which turns gear G8. Gear G1 alsoturns gear G3 which turns gear G5 which turns gear G7 which turns gearG8. The gear ratio between gear G1 and gear G8 is 2:1.

The heliostat of embodiment ‘4’ will now be described with reference toFIGS. 10 and 11. The linkages and motors of the heliostat are mounted ona carriage similar that that of embodiments ‘1’ and ‘2’.

Tilt motor 4102 is mounted to tilt motor plate 4605. The shaft of tiltmotor 4605 is fixed directly to the mirror frame guides 4202. Incidencelinkage 4303 is connected at one end to reflection linkage 4606 andfixed to sensor plate 4801 at its other end. Incidence linkage 4403 isconnected at one end to reflection linkage 4605 and fixed to sensorplate 4801 at its other end. The joints between linkages 4303 and 4606and between linkages 4403 and 4605 are rotatable. Traversing bolt 4503passes through linkages 4303 and 4403 and through mirror frame guides4201 and 4202.

Sensors 4802, 4803, 4804, and 4805 are located on sensor plate 4801. Panmotor 4101 rotates the heliostat carriage until the sunlight incident onpan sensors 4804 and 4805 is balanced. Tilt motor 4102 rotates theguides 4201 and 4202 until the sunlight incident on tilt sensors 4802and 4803 is balanced. When each sensor pair is balanced, sensor plate4801 has achieved a position wherein it is perpendicular to theincidence vector. When sensor plate 4801 is aligned perpendicular to theincidence vector, incidence linkages 4303 and 4403 are perpendicular tothe incidence vector.

Reflection linkages 4605 and 4606 are fixed to the carriage posts 4603such that linkages 4605 and 4606 are perpendicular to the main shaft4001. Since main shaft 4001 is collinear with the receiver, reflectionlinkages 4605 and 4606 are always perpendicular to the reflectionvector.

When incidence linkages 4303 and 4403 and reflection linkages 4605 and4606 are aligned to positions perpendicular to the incidence andreflection vectors respectively, the mechanism comprising the linkages,traversing bolts, guides, and mirror frame achieves a mirror positionnecessary for imaging.

The heliostat of embodiment ‘5’ will now be described with reference toFIGS. 12 through 14. The heliostat of embodiment ‘5’ is similar in formand function to the heliostat of embodiment ‘4’ with the notabledifference that the carriage of the heliostat of embodiment ‘5’ issimplified in comparison to the heliostat of embodiment ‘4’. Thereflection linkage 5300 is mounted directly on the main shaft 5001. Panmotor 5101 and tilt motor 5102 are mounted directly on the reflectionlinkage 5300. The main shaft 5001 is keyed to accept a slotted shaft ofpan motor 5101.

The heliostat of embodiment ‘6’ will now be described with reference toFIGS. 15 through 18. The heliostat of embodiment ‘6’ is similar in formand function to the heliostat of embodiment ‘5’ with a notabledifference. The incidence linkage 6807, reflection linkage 6300, andtraversing bolt 6505 operate in a slot in part 6806 that is parallel tothe normal of the mirror 6204 (as opposed to a slot that is parallel tothe mirror 6204).

1. A radiation reflection device comprising: a reflective surface forreflecting incident radiation from a moving radiation source to areceiver; a mirror frame wherein; said mirror frame is fixed to saidreflective surface; mirror frame guides wherein; said mirror frameguides are fixed to said mirror frame; said mirror frame guides compriseone or more parallel slots; one or more incidence linkages and one ormore reflection linkages wherein; said incidence linkages are alignedperpendicular to the incidence vector; said reflection linkages arealigned perpendicular to the reflection vector; said incidence linkagesand said reflection linkages are interconnected in a parallelogrampattern; vertices of said parallelogram pattern define a parallelogrambisecting line that bisects the angle between said incidence linkagesand said reflection linkages; one or more traversing bolts wherein; eachof said traversing bolts intersects one of said vertices of saidparallelogram bisecting line; each of said traversing bolts passesthrough one or more incidence linkages, one or more reflection linkagesand one or more of said slots of said mirror frame guides; a main shaftwherein; said mirror, said mirror frame, said incidence linkages, andsaid reflection linkages, are rotatable about said main shaft; saidmirror, said mirror frame, said incidence linkages, and said reflectionlinkages are mounted, either directly or indirectly, on said main shaft.2. A device of claim 1 wherein said radiation reflection device isimplemented in a heliostat wherein said radiation reflection devicecomprises: a tilt motor wherein; one of said incidence linkages isrotated, directly or indirectly, by said tilt motor; one or more of saidreflection linkages is mounted, directly or indirectly, to said mainshaft wherein said main shaft is aligned along the reflection vector; apan motor wherein; said pan motor is connected to said main shaft; saidpan motor can cause said mirror, said mirror frame, said incidencelinkages, and said reflection linkages to rotate about said main shaft.3. A device of claim 2 wherein said radiation reflection device furthercomprises a sensor plate fixed to one or more of said incidence linkageswherein; said sensor plate includes a pair of pan sensors; said sensorplate includes a pair of tilt sensors; said pan sensors produce acontrol signal which can be used to control said pan motor; said tiltsensors produce a control signal which can be used to control said tiltmotor.
 4. A device of claim 1 wherein said radiation reflection deviceis implemented in a ganged array wherein; said radiation reflectiondevice comprises a cable wherein: said cable provides a reflectionaiming means; said cable is connected at one end to said receiver; saidcable is connected at one end to one of said reflection linkages; saidcable causes one or more of said reflection linkages to be alignedperpendicular to the reflection vector; said main shaft is aimed by anincidence aiming means; said main shaft is continually adjusted by saidincidence aiming means to align the central axis of said main shaft withthe incidence vector; one or more of said incidence linkages is mounted,directly or indirectly, to said main shaft causing said incidencelinkages to be aligned perpendicular to said incidence vector.